1. Field of the Invention
The present invention is a printing apparatus and a printing method for forming various information such as images and characters on a plurality of types of recording medium or transfer medium, and more particularly relates to a printing apparatus and a printing method that can accurately press against a plurality of types of recording medium or transfer medium having different degrees of hardness to form that information.
2. Description of the Related Art
Conventionally, thermal transfer method printing apparatuses that record desired images and characters by thermally transferring using a thermal head via a thermal transfer film to a recording medium are used to create card shaped recording medium, like credit cards, cash cards, license cards and ID cards. An example can be found in Japanese Patent Publication (Tokkai) 09-131930, which teaches a direct transfer method printing apparatus that directly transfers images and characters to a recording medium via thermal transfer film. The use of a thermal sublimate ink has the benefit of attaining high quality images because this type of ink is more expressive. However, a receptive layer to receive ink on the surface of a recording medium to which images, etc., are transferred is an essential element to make this method of printing possible. Therefore, there is the problem that the types of recording medium that can be used is limited, or else it is necessary to form a receptive layer upon the surface of a recording medium.
Generally, cards made of polyvinyl chloride (also known as PVC cards) are widely used as a recording medium because they can receive thermal sublimate ink. However, due to the fact that harmful substances are generated when these cards are burned, consideration is being given to switching to cards made of polyethylene terephthalate (also known as PET cards). However, because PET cards are made of a crystallized material, they are not only difficult to use in a thermal sublimate transfer process, but they are also difficult to use in embossing. For that reason, when it is necessary to emboss the recording medium, PCV will have to be used well into future.
Furthermore, in recent years, there are card shaped media that have IC chips or antennae embedded therein. Such IC cards are used in a variety of fields. Because there is an object embedded in the card, the surface of the card ends up being uneven which results in image transfer problems.
Japanese laid-open patent publication 8-332742 teaches the technology of a thermal transfer method printing apparatus that overcomes the aforementioned problems in an indirect transfer method printing apparatus that transfers an image to an intermediate transfer medium once, then transfers that image again to the recording medium. According to this method, it is possible to overcome the problems of the direct transfer method, such as the limit to the type of recording medium, related to the receptive layer, or the problem of the transferring of images to an uneven surface of the recording medium, both of which are considered to be demerits of direct transfer printing. Furthermore, this method has the advantage of being easier to printing to the entire surface of the card shaped recording medium compared to the direct transfer method.
Still further, Japanese laid-open patent publication 8-58125 discloses a thermal transfer printing apparatus that is structured to dually use a thermal head to transfer ink to an intermediate transfer film to transfer and form an image thereupon, then to retransfer that ink image to a recording paper using a heat roller, and to use a thermal head which is different to the aforementioned thermal head to transfer ink to the back side of a recording paper, to print to both the front and back sides of a recording paper.
However, running costs associated with the intermediate transfer method are higher than those for the direct transfer method because an intermediate transfer medium must be used. Printing also takes longer. Furthermore, depending on the design of the card, even if the entire front surface is required for printing, often times the back side is used only to print precautions for card use. Therefore, there are fewer cases requiring printing over the entire surface, so there are merits and demerits for both methods of printing. Therefore, if there were a printing apparatus that can switch between the printing methods of a direct transfer method and an indirection transfer method to print images to a recording medium according to the characteristic of a recording medium, including the quality of the material of the recording medium, like PVC or PET, or whether or not it is embossed or includes IC elements, and whether it is necessary to print to the entire surface of the recording medium, it would be possible to transfer (or print) using the method best suited that particular recording medium. This, in turn, would reduce the running costs that are associated with printing. Also, by sharing a part of the members between the direct transfer method and the indirect transfer method the entire printing apparatus can remain smaller and this would enable a printing apparatus with reduced running costs. Therefore, it is conceivable that an apparatus thus capable would become quite widely used. However, because there is a difference in hardness, caused by the thicknesses or structure comprised by each of a recording medium, such as a card formed with print information such as images by a thermal head and an intermediate transfer medium such a intermediate transfer film, it is difficult to attain high quality images under the same image transfer conditions.
Specifically, on printing apparatuses that comprise a thermal head, often times a platen roller is used to support a recording medium (or transfer medium) interposed therebetween a thermal head by an ink ribbon during printing. Rubber rollers are generally used for the platen roller, thus if the pressing force of the thermal head is constant when forming images onto a less-hard transfer medium with the pressing force having a value set for a harder transfer medium, the uneven surface of the platen roller can affect the less-hard transfer medium thereby causing transfer defects, or so-called insufficient or missing transfers onto the transfer medium. Needless to say, this notably reduces the quality of the image that is transferred. A relatively less-hard platen roller can also have an affect. It is conceivable to employ a platen roller with a higher degree of hardness, but if there is dirt or other foreign matter adhering thereto the surface, that area thereof cannot be reproduced, rather that hollowed area is supported which causes poor transfers, such as missing transfers when forming the next image. Therefore, it is necessary for the degree of hardness of a platen roller be lowered somewhat and to have some resilience. On the other hand, if an image is formed on a transfer medium that has a higher degree of hardness using a pressure set for a transfer medium that has a lower degree of hardness, with the pressure of the thermal head at a constant, this will hinder transport when forming an image onto the transfer medium because the pressing contact force for both is too large. This will speed up the wear-out of the thermal head or it can cause new problems such as scratching, cracking or otherwise degrading of the ink ribbon and making it difficult to achieve satisfactorily formed images.
For that reason, it is preferable to form images by changing the pressing force of the thermal head for a plurality of transfer medium types. Prior art, such as that disclosed in Japanese Patent Publication (Hei) 5-24305, teaches a technology of a head pressing apparatus on a printer to vary the pressing force of the thermal head. With this technology, the pressing force is set high for paper which is thicker than regular copy paper, such as a post card, and set slightly lower for such regular copy paper considering the amount to subtract according to the strength of that paper. This ensures a quality print when printing to paper that has differing thicknesses and degrees of smoothness.
Although the technology disclosed in Japanese Patent Publication (Hei) 5-24305 ensures the printing quality on paper having different thicknesses and degrees of smoothness, when considering its application to a printing apparatus that can transfer both directly and indirectly, the differences in hardness of a hard card-shaped recording medium and the soft, pliable quality of film-shaped transfer medium make it difficult to ensure a good quality print using both transfer methods. A high degree of printing quality, free of missing transfers, is particularly required on card-type recording medium because they also function as personal IDs, regardless of the either the direct transfer method or the indirect transfer method.
An object of the present invention is to provide a printing apparatus and a printing method that can ensure high quality printed images free of missing transfers on a plurality of media, regardless of the type of transfer method used.
According to the first aspect of the present invention, at least one printing means for forming images on a plurality of transfer medium having differing degrees of hardness is provided, and pressing application means for applying a pressure to the aforementioned printing means so that the pressure applied to a soft first transfer medium is higher than the pressing force applied to a hard second transfer medium when forming images to the aforementioned transfer medium, on a printing apparatus that forms images onto a transfer medium with the printing means pressed against the transfer medium.
According to this aspect of the invention, when forming images to a plurality of transfer medium that have differing degrees of hardness, on at least one printing means for forming an image, a pressure is applied by the pressure application means to a soft first transfer medium, that is higher than the pressure applied to a harder second transfer medium, and an image is formed to a transfer medium by the printing means being pressed against the transfer medium. According to this aspect, the pressure application means applies a pressure to the softer first transfer medium that is larger than the pressure to a hard second transfer medium on the printing means, so the appropriate amount of pressure can be applied to the transfer medium regardless of the degree of its hardness, thereby ensuring high quality printing that does not have missing transfers. An example for a first transfer medium could be a film-shaped transfer medium and for a second transfer medium, an example could be a card-shaped transfer medium that comprises a predetermined hardness.
In this embodiment, a first mode for forming an image onto a first transfer medium, mode setting means for setting a second mode for forming an image on a second transfer medium, and pressure control means for controlling the pressure applied to printing means by a pressure application means according to the first or the second mode as set by that mode setting means. The pressure applied to the printing means by the pressure application means is controlled by the pressure control means to vary according to the mode that is set by the mode setting means, so it is possible to apply pressure to the printing means that is appropriate for the transfer method (or the mode) in use. Also, provided are detection means for detecting the existence of the first transfer medium and pressure control means for controlling the amount of pressure to apply to the printing means by the pressure application means, based on a detection signal from that detection means. When this detection means detects the existence of the first transfer medium, a high amount of pressure is applied to the printing means by the controls from the pressure control means. This eliminates miss-operation between the first and second transfer medium.
If the structure of the pressure application means includes an advancing and retreating movement regulation member that advances and retreats the printing means between an image forming position and a retracted position separated from the image forming position, and a resilient member for absorbing resistance that is generated in the direction opposite to the direction of pressure onto the first transfer medium or the second transfer medium of the printing means, the position thereof regulated by the advancing and retreating movement regulation member. The pressure application means can ensure the advancing and retreating operations with regard to the pressure between the printing means image forming position and the retreated position using the advancing and retreating movement regulation member. Because the resilient member absorbs the resistance at the image forming position of the printing means that is generated in the direction opposite to the pressing direction with regard to the transfer medium, it is possible to hold the pressure to a predetermined pressure on the first or the second transfer medium. For the advancing and retreating regulating member, it is acceptable, for example, to furnish a first reference position that applies a large pressure on a first transfer medium, a second reference position that applies a small pressure to a second transfer medium and a third reference position that does not apply pressure to either the first or the second transfer medium on an eccentric cam that comprises an outer surface.
A second aspect of the present invention is a printing apparatus comprising first printing means for forming an image on a recording medium, second printing means for forming an image on an intermediate transfer medium that temporarily holds an image, transfer means for transferring the image on the intermediate transfer means to the same recording medium above or a different recording medium, and advancing and retreating means for advancing and retreating the first and the second printing means from an image forming position and a position separated from the image forming position. The pressure on the intermediate transfer medium at the second printing means when the second printing mean is positioned at the image forming position by the advancing and retreating means is configured to be greater than the pressure on the recording medium of the first printing means when position at the image forming position by the advancing and retreating means.
According to this aspect of the invention, the first printing means that forms an image onto a recording medium, and the second printing means for forming an image onto an intermediate transfer medium that temporarily holds an image advance and retreat by the advancing and retreating means between an image forming position and a position separated therefrom. When the first and second printing means are positioned at the image forming position by the advancing and retreating means, the pressure on the intermediate transfer medium of the second printing means is greater than the pressure on the recording medium of the first recording medium. Accordingly, when the first and the second printing means are positioned at each of the image forming positions by the advancing and retreating means, the pressure on the intermediate transfer medium of the second printing means is configured to be higher than the pressure on the recording medium of the first printing means. This applies a higher pressure on the intermediate transfer medium which has a lower degree of hardness, than the pressure applied to the recording medium which has a higher degree of hardness, so the appropriate amount of pressure can be applied to both types of recording medium, regardless of whether the transfer medium or the recording medium have a high low degree of hardness. This ensures high quality printing without missing transfers. In this aspect of the invention, an example for a recording medium could be a card-shaped transfer medium that comprises a predetermined hardness and for the intermediate transfer medium, an example could be a transfer medium formed onto a film-shaped media.
Furthermore, according to this aspect, further provided are mode setting means for setting a first mode for transferring an image on an intermediate transfer medium to a recording medium using a transfer means after forming an image onto the intermediate transfer medium by the second printing means, or to a different recording medium, and a second mode for forming an image onto a recording medium using the first printing means, and pressure control means for controlling the pressure applied to the first or the second printing means that are positioned at the image forming position by the advancing and retreating means, according to the first or the second mode set by the mode setting means. Because the pressure control means controls the pressure being applied to the first or the second printing means positioned at the image forming position by the advancing and retreating means to vary accordingly, the pressure which is appropriate to that printing means can be applied thereto. Also provided are detection means for detecting the existence of the intermediate transfer medium, and pressure control means for controlling the amount of pressure applied to the second printing means that is positioned at an image forming position by the advancing and retreating means to be larger than the pressure applied to the first printing means positioned at an image forming position by the advancing and retreating means, based on a detection signal from that detection means. When detection means detect the existence of the intermediate transfer medium, the pressure control means controls so that a high amount of pressure is applied to the first printing means that is positioned at an image forming position by the advancing and retreating means. This eliminates miss-operation between the intermediate transfer medium and the recording medium.
The advancing and retreating means comprises an eccentric cam that regulates the amount of movement in the advancing or retracting movement of the first printing means and the second printing means. The rotation of this eccentric cam is structured to position the first printing means or the second printing means at an image forming position. The advancing and retreating means can also comprise a resilient member to absorb resistance in the pressure generated by the first printing means and the second printing means. Still further, the first printing means and the second printing means comprise a thermal head to perform a thermal transfer. It is perfectly acceptable for the eccentric cam and resilient member to be arranged in pairs in the same direction on the length direction of the thermal head. Also, the first printing means and second printing means print elements can be configured with the same printing elements.
Still further, a third aspect of the invention is a printing method. In this method, a card-shaped recording medium having a predetermined hardness is transported to an image forming position. It includes a first printing process for forming an image on that recording medium at that image forming position, and a second printing process that transports a film-shaped intermediate transfer medium that temporarily holds an image to that image forming position, then after the forming of an image thereupon at that image forming position, it transports that intermediate transfer medium to an image transfer position while also transporting that card-shaped recording medium or a different card-shaped recording medium to that image transfer position and transfers the image formed on the intermediate transfer medium at that image transfer position to that card-shaped recording medium or a different card-shaped recording medium to form an image thereupon. In this method, the pressure on the film-shaped intermediate transfer medium when forming an image thereupon in the second printing process is configured to be higher than the pressure applied to the card-shaped recording medium when forming an image there in the first printing process.
These and other objects, aspects and embodiments of the present invention will now be described in more detail with reference to the following drawing figures.